Breech mechanism with interchangeable chamber inserts for caseless and case-type cartridges

ABSTRACT

A breech mechanism for firearms includes a chamber insert adapted to be secured in the camber of a rifle or the like for easily converting the rifle to fire either caseless cartridges or standard case-type cartridges depending upon the insert used. A modified bolt is provided for use with the chamber insert.

United States Patent Brown [451 Apr. 18, 1972 [54] BREECH MECHANISM WITH1 322 31 Alrmli: ..42/77 1B C ar son et a1 42/76 A ANDECRASE 2,297,69310/1942 Dicke 42/16 R 2,585,195 2/1952 Walker ..42/16 R TYPE CARTRIDGES2,476,232 7/1949 Williams ....42/76 R Inventor: Daniel M. Brown, 806Hampshire, Grand 3,008,258 11/1961 Johnson ..42/l6 R 75050 PrimaryExaminer-Benjamin A. Borchelt 22 Filed; 21, 1970 Assistant Examiner-C.T. Jordan Attorney-Shoemaker & Mattare [21] Appl. No.: 30,438

[57] ABSTRACT [52] U.S. Cl. ..42/76 R, 42/16 A breech mechanism forfirearms includes a chamber insert [51] Int. Cl. ..F41c 21/12, E4lc11/00 adapted to be secured in the camber of a rifle or the like for[58] Field of Search ..42/76, 76 A, 77, 16 R; easily converting therifle to fire either caseless cartridges or 89/14 R standard case-typecartridges depending upon the insert used.

A modified bolt is provided for use with the chamber insert. [56]References Cited V v UNITED STATES PATENTS 7 Claims, 8 Drawing Figures329,793 11/ 1885 Wheeler ..42/77 PATENTED R 1 8 I912 3.656.250

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INVENTOR DANIEL M. BROWN B wmm ATTORNEYS PATENTEDAPR 181972 3 6 56 2 5O-sum 2 OF 2 FIG.4.

INVENTOR DANIEL M. BROWN ATTORNEYS BREECH MECHANISM wrrn INTERCHANGEABLECHAMBER INSERTS FOR CASELESS AND CASE-TYPE CARTRIDGES BACKGROUND OF THEINVENTION The present invention relates to means for converting a rifleto fire either caseless cartridges or standard case-type cartridges.

A chamber insert is provided for threading into the chamber of a rifleor the like and in one form includes a generally cylin drical flexibleside wall portion for use with caseless cartridges and includes meansfor holding the caseless cartridge in the breech of a rifle or the likein a gas-tight manner. A special bolt is provided for use with thechamber insert and includes an elongate cylindrical portion adapted tobe disposed in surrounding relationship to the cylindrical flexible sidewall of the chamber insert.

.In another form of the invention, a chamber insert is provided forthreading into the chamber of the rifle for use with standard case-typecartridges and includes a standard bolt for use with the standardchamber insert.

The bolts and chamber inserts are readily interchangeable inconventional rifles for converting the rifle from use with standardcase-type cartridges to use with caseless cartridges.

OBJECTS OF THE INVENTION It is an object of the invention to provide abreech mechanism for firearms for readily converting the firearms fromuse with standard case-type cartridges to use with case less cartridgesand vice versa.

It is another object of this invention to provide a chamber insert andbolt specially constructed to be readily inserted and removed from thebreech of the rifle or the like for converting a rifle from use withstandard case-type cartridges for use with caseless cartridges.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view inelevation of a rifle incorporating the chamber insert and bolt forfiring caseless cartridges.

FIG. 2 is a sectional view in elevation of a rifle incorporating thechamber insert and bolt for use with case-type cartridges; FIG. 3 is anexploded view partly in section showing the manner in which a spannerwrench is used for inserting and removing the chamber insert from arifle for firing caseless cartridges;

FIG. 4 is a sectional view in elevation illustrating the breech andbarrel of a rifle with the chamber insert and bolt removed;

FIG. 5 is a sectional view in elevation of the chamber insert for usewith caseless cartridges;

FIG. 6 is a sectional view in elevation of the special bolt used withthe chamber insert for firing caseless cartridges;

FIG. 7 is a sectional view in elevation of the chamber insert for usewith standard case-type cartridges; and

FIG. 8 is a sectional view in elevation of the bolt for use with thechamber insert for firing case-type cartridges.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings,wherein like reference numerals refer to like parts throughout theseveral views, the form of the invention for use with caselesscartridges is depicted in FIGS. 1, 5 and 6. The barrel of a rifle or thelike is indicated generally at 1 and includes a reduced end portion 2threaded externally at 3 and on which is threaded a Mauser type breech 4threaded internally at 5 for mating cooperation with the externalthreads 3 on the reduced end portion 2 of barrel 1. The breech 4includes a bore 6 therethrough for receiving a Mauser type bolt 7 andhas locking lug recesses 6' therein for receiving the locking lugs 8 ofthe bolt 7, which is shown at battery position in FIG. 1. A bore 9 isformed lengthwise through the barrel and is enlarged at one end at 10and has internal threads 11 thereon, the bore 10 being joined 12. Thechamber insert is depicted generally at 13 and has a bore 14therethrough substantially commensurate in diameter with the rifle bore9. The bore 14 includes an arcuately shaped enlarged bore portion 15extending from one end of the insert to adjacent the other end thereofand defines a relatively thin, tapered cylindrical side wall 16 made,for example, of flexible spring steel or the like. One end of thechamber insert is externally threaded at 17 for mating cooperation withthe internal threads 11 in the bore of the rifle barrel. Afrusto-conical shoulder 18 is formed on said one end of the chamberinsert and abuts the reference cone or surface 12 in the barrel in agas-tight manner when the chamber insert is properly seated in thechamber. A caseless cartridge C is fitted within the chamber insert andincludes a propellant 19 substantially filling the arcuately taperedcylindrical cavity within the chamber insert. A projectile 20 isreceived within the reduced bore portion 14 of the chamber insert andextends into bore 9 of the barrel 1. The Mauser type bolt 7 includes anelongate cylindrical relatively thin-walled projection or sleeve 21disposed in close surrounding relationship to the side wall 16 of thechamber insert. An ignition bore or opening 22 is formed longitudinallythrough the bolt 7 establishing communication between the chambercontaining the propellant l9 and an ignition source which may comprise aprimer or an electrical ignition or the like.

The chamber insert 13 described above is inserted and removed from thebreech by means of a spanner wrench indicated generally at W in FIG. 3and which includes an elongate cylindrical shank portion 49 havinglongitudinally projecting lugs 50 at one end thereof for cooperativeengagement in recesses R formed adjacent the threaded portion of thechamber insert 13. A handle 51 is fitted laterally in the other end inthe spanner wrench for turning the wrench to thread the chamber insertinto and out of the recess within the barrel.

Referring now to FIG. 2, that form of the invention for use withstandard case-type cartridges is depicted. A rifle barrel 23 has alongitudinal bore 24 extending therethrough enlarged at one end at 25and internally threaded in the enlarged bore portion at 26. Afrusto-conical reference cone or surface 27 joins the threaded boreportion 26 with the bore portion 24. The end of the barrel is externallythreaded at 28 and a breech 29 internally threaded at 30 is threadablyreceived thereover. A longitudinal bore 31 extends through the breechand includes locking lug recesses 32 at one end for receiving thelocking lugs 33 of a bolt 34 received in the bore 31 of the breech. Astandard chamber insert 35 is secured within the enlarged bore portion25 of the barrel by means of external threads 36 thereon in cooperativeengagement with the threads 26 in the barrel. The forward end of thechamber insert has a frusto-conical shoulder or surface 37 thereon intight abutting contact with reference surface 27, which forms agas-tight fit when the chamber insert is properly seated. A longitudinalbore is formed through the chamber insert and includes a first portion38 at one end substantially commensurate in diameter with the diameterof rifle bore 24 and a second portion 39 enlarged relative to portion38, the two portions being joined by a tapered shoulder 40.

A standard case-type cartridge indicated generally at C is receivedwithin the chamber insert and includes a generally cylindrical side wall41 of brass or the like with a rim 42 at one end thereof disposed overthe end of the side wall of the chamber insert in abutting relationshipthereto. A percussion cap or primer 43 is fitted centrally within thebase of the cartridge for igniting a propellant 44 substantially fillingthe case to fire a projectile 45 through the bore of the rifle.

The bolt 34 fitted within the bore 31 in breech 29 is shown at batteryand has a longitudinal bore 46 through the center thereof in which isslidably received a firing pin 47 for striking the percussion cap orprimer 43 to fire the projectile 45 from the barrel of the rifle. Theend of the bolt includes a shallow recess 48 for receiving the raisedportion of the base of carwith the bore 9 by a frusto-conical referencecone or surface tridge C.

FIGS. 4 through 8 illustrate the interchangeability of thecaseless-cartridge chamber insert and bolt with the standard case-typechamber insert and bolt. In FIG. 4, a typical rifle barrel and breechmechanism, such as described in H0. 2, is shown assembled together, thebarrel 23 including a bore 24 therethrough enlarged at one end at 25 andinternally threaded at 26 for matingly receiving the threads of one ofthe insert chambers therein. A reference cone or surface 27 is formedbetween the threaded end of the enlarged bore 25 and bore 24 againstwhich one end of the chamber insert is adapted to be seated in agas-tight manner.

FIG. and 6 illustrate the chamber insert and bolt, respectively, for usewith caseless cartridges and in order to adapt the rifle mechanismillustrated in FIG. 4 to use with caseless cartridges, the chamberinsert 13 is threaded into the enlarged bore portion 25 by use of thespanner wrench W, with the threads 17 on the end of the insert chamberin mating engagement with threads 26 within the bore of barrel 23. Thechamber insert is threaded into the bore until the reference cone orfrusto-conical end of the insert comes into tight fitting abuttingcontact with the reference cone or surface 27 within the bore of therifle. The bolt 7 is then fitted into place by sliding the boltlongitudinally in the bore 31 with the cylindrical sleeve 21 fitting intight surrounding relationship with side wall 16 of the chamber insertand with the locking lugs 8 received in the locking lug recesses 32 inthe breech mechanism 29 when the bolt is at battery.

Alternatively, the rifle mechanism may be converted for use withstandard case-type cartridges by removing the bolt and chamber insertdescribed above and threading the chamber insert 35 into place with thethreads 36 on one end thereof in mating engagement with threads 26 untilthe reference cone or end 37 of the chamber insert come into tightfitting abutting contact with the reference cone or surface 27 withinthe bore of the rifle. The standard bolt 34 is then fitted into positionwith locking lugs 33 received in the locking lug recesses 32 in thebreech mechanism.

Both forms of the invention provide a secure gas-tight fit within thebreech of the rifle thus insuring reliable and efiective firing of acartridge received therein. For example, the reference surfaces 12 and18 and 27 and 37 are fitted in gastight engagement and the cylindricalside walls of the chamber inserts are slightly flexible and accordinglyflex outwardly into close fitting gas-tight engagement with the sleeve21 or the wall of bore 25 as the case may be when the cartridge isfired.

The components of both forms of the invention described hereinbefore arereadily manufactured with production equipment. For example, theclearance between the exterior of the sleeve 21 and the bore of thebarrel should be maintained from about 0.001 inches to 0.002 incheswhich is easily achieved with production equipment.

As this invention may be embodied in several forrns without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, and since thescope of the invention is defined by the appended claims, all changesthat fall within the metes and bounds of the claims or that form theirfunctional as well as conjointly cooperative equivalents are thereforeintended to be embraced by those claims.

lclaim:

l. A breech mechanism for firearms for selectively converting a firearmto fire a caseless cartridge and case-type cartridge, comprising a firstelongate chamber insert and a second elongate chamber insert, said firstand second inserts being independently used one at a time in a firearm,and each insert having an externally threaded forward end portion forcooperative threaded engagement with internal threads in a rearward endportion of the barrel of said firearm, said forward end portion of eachsaid insert being externally conically tapered to effect a gas-tightseal with a mating, conically tapered reference surface in said barrel,a longitudinal bore extending through each said insert and having adiameter at the forward end thereof substantially the same as thediameter of the bore of the barrel of said firearm, the remainder ofsaid bore in each insert being diametrically enlarged and extending overa major portion of the length of each said insert to define a cartridgereceiving chamber having a relatively thin, flexible, rearwardlyextending cylindrical side wall so that upon explosion of a cartridgereceived in said cartridge receiving chamber, said cylindrical side wallflexes outwardly to effect a gas-tight seal with said firearm, and firstbolt means and second bolt means for cooperation with a respectivechamber insert and with said firearm for firing a cartridge received insaid fireann, said inserts and said bolt means being readilyinterchangeable in said firearm to quickly and easily convert saidfirearm from use with case-type cartridges to use with caselesscartridges and vice versa.

2. A breech mechanism as in claim 1, wherein: said enlarged bore portionin said first insert is arcuately tapered with an increasing diameterfrom the forward end thereof to the other end thereof so that saidcylindrical side wall has a gradually decreasing thickness toward therearward end thereof; and said first bolt means includes alongitudinally extending sleeve for close fitting disposition aroundsaid cylindrical side wall, said first insert and said first bolt meansconstructed to fire a caseless cartridge.

3. A breech mechanism as in claim 2, wherein: a longitudinal ignitionbore is formed through said first bolt for firing said caselesscartridge.

4. A breech mechanism as in claim 1, wherein: said enlarged bore portionin said second insert is cylindrical and has an end surface at therearward end thereof against which the rim of a case-type cartridge isadapted to be seated; said bolt including a recess in the forward endthereof for receiving a raised portion at the base of said case-typecartridge when said second bolt and said second insert are assembled ina firearm with a case-type cartridge fitted in said second insert.

5. A breech mechanism as in claim 4, wherein: a longitudinal bore isformed through said second bolt and a firing pin is slidably fittedwithin said bore for firing a cartridge in said second insert.

6. A breech mechanism as in claim 1, wherein each said chamber insert isconstructed of flexible spring steel.

7. A breech mechanism for firearms for selectively converting a firearmto fire a caseless cartridge and a case-type cartridge,, comprising afirst elongate chamber insert and a second elongate chamber insert, saidfirst and second inserts being independently used one at a time in afirearm, and each insert having releasable securing means thereon forcooperative engagement with complementary securing means in saidfirearm, each of said inserts having a rearwardly extending cylindricalside wall defining a cartridge receiving chamber therein and constructedso that upon explosion of a cartridge received in said cartridgereceiving chamber, said insert effects a gas-tight seal with saidfirearm, and bolts means for cooperation with said chamber inserts andwith said firearm for firing a cartridge received in said firearm, saidinserts being readily interchangeable in said firearm to quickly andeasily convert said firearm from use with case-type cartridges to usewith caseless cartridges and vice versa.

1. A breech mechanism for firearms for selectively converting a firearmto fire a caseless cartridge and case-type cartridge, comprising a firstelongate chamber insert and a second elongate chamber insert, said firstand second inserts being independently used one at a time in a firearm,and each insert having an externally threaded forward end portion forcooperative threaded engagement with internal threads in a rearward endportion of the barrel of said firearm, said forward end portion of eachsaid insert being externally conically tapered to effect a gas-tightseal with a mating, conically tapered reference surface in said barrel,a longitudinal bore extending through each said insert and having adiameter at the forward end thereof substantially the same as thediameter of the bore of the barrel of said firearm, the remainder ofsaid bore in each insert being diametrically enlarged and extending overa major portion of the length of each said insert to define a cartridgereceiving chamber having a relatively thin, flexible, rearwardlyextending cylindrical side wall so that upon explosion of a cartridgereceived in said cartridge receiving chamber, said cylindrical side wallflexes outwardly to effect a gas-tight seal with said firearm, and firstbolt means and second bolt means for cooperation with a respectivechamber insert and with said firearm for firing a cartridge received insaid firearm, said inserts and said bolt means being readilyinterchangeable in said firearm to quickly and easily convert saidfirearm from use with case-type cartridges to use with caselesscartridges and vice versa.
 2. A breech mechanism as in claim 1, wherein:said enlarged bore portion in said first insert is arcuately taperedwith an increasing diameter from the forward end thereof to the otherend thereof so that said cylindrical side wall has a graduallydecreasing thickness toward the rearward end thereof; and said firstbolt means includes a longitudinally extending sleeve for close fittingdisposition around said cylindrical side wall, said first insert andsaid first bolt means constructed to fire a caseless cartridge.
 3. Abreech mechanism as in claim 2, wherein: a longitudinal ignition bore isformed through said first bolt for firing said caseless cartridge.
 4. Abreech mechanism as in claim 1, wherein: said enlarged bore portion insaid second insert is cylindrical and has an end surface at the rearwardend thereof against which the rim of a case-type cartridge is adapted tobe seated; said bolt including a recess in the forward end thereof forreceiving a raised portion at the base of said case-type cartridge whensaid second bolt and said second insert are assembled in a firearm witha case-type cartridge fitted in said second insert.
 5. A breechmechanism as in claim 4, wherein: a longitudinal bore is formed throughsaid second bolt and a firing pin is slidably fitted within said borefor firing a cartridge in said second insert.
 6. A breech mechanism asin claim 1, wherein each said chamber insert is constructed of flexiblespring steel.
 7. A breech mechanism for firearms for selectivelyconverting a firearm to fire a caseless cartridge and a case-typecartridge, comprising a first elongate chamber insert and a secondelongate chamber insert, said first and second inserts beingindependently used one at a time in a firearm, and each insert havingreleasable securing means thereon for cooperative engagement withcomplementary securing means in said firearm, each of said insertshaving A rearwardly extending cylindrical side wall defining a cartridgereceiving chamber therein and constructed so that upon explosion of acartridge received in said cartridge receiving chamber, said inserteffects a gas-tight seal with said firearm, and bolts means forcooperation with said chamber inserts and with said firearm for firing acartridge received in said firearm, said inserts being readilyinterchangeable in said firearm to quickly and easily convert saidfirearm from use with case-type cartridges to use with caselesscartridges and vice versa.